Steam generator



Ap 28, 1953 E. e. BAILEY ETAL STEAM GENERATOR 7 Sheets-Sheet 1 FiledApril 8, 1949 INVENTOI QS Erv/n G Halley & BY Ro/p/r M HardgroveAfiORNEY Q c F owm lllllllnvll l ||||l||| & i1

April 28, 1953 E. G. BAILEY ETAL STEAM GENERATOR '7 Sheets-Sheet 2 FiledApril 8, 1949 MQ mg m% w% 5 Mr Em M EQ e y w mww mm w m m m I. n Y BATTORNEY '7 Sheets-Sheet .3

E. G. B'HLEY ErAL STEAM GENERATOR NE. ww\ 0% 0w 0% Mam000000000000000000000009 000000000000000000000000000O0O00000000000000000000000000 00000000000000000000000000000000000000000000000 0000000000000000000000000 000000000000000000000000 O000000000000000000000000 000000000000000000000000000000000000000000 000000000000000000 00000000000 April 28, 1953 FiledApril 8, 1949 INVENTORS' Erv/n G. Ba/leg 5 ATTORNEY A ril 28, 1953 5;.e. BAILEY EI'AL STEAM 'GENERATOR 7 Sheets-Sheet 4 Filed April 8, 1949 &w

m W NM -Nm D" Y B ATTORNEY April 3, 1953 E. e. BAILEY ETAL 2,636,484

' STEAM GENERATOR Filed April 8, 1949 7 Sheets-Sheet 6 v I N 1- KO gINVENTORS Ervin G. Bar/72y &

f Y Ralph M. Hardgrove WW ATTORNEY April 28, 1953 E. G. BAILEY EI'ALSTEAM GENERATOR Filed April 8. 1949 7 Sheets-Sheet 7 m NK g fi Q we 0 QQ DON II u 11 5 m 1 i MM mmw am m o w 1 N w INVENTORS Erv/n G Bailey 3BY Ralph M Hardgrove ATTORNEY which would interfere with Patented Apr.28, 1953 STEAM GENERATOR Ervin G. Bailey, Easton, Pa., and Ralph M.Hardgrove, Canton, Ohio, assignors to The Eabcock & -Wilcox Company,Jersey City, N. J., a corporation of New Jersey Application April 8,1949, Serial No. 86,174 V a This invention relates to a steam generatinginstallation of the water tube type.

The invention, more particularly, relates to a water tube steamgenerator adapted for operation at high capacities and high steampressures and for the effective use of pulverized fuel in the furnace ofthe installation.

'The steam generator of the invention is particularly adapted for theefficient generation of steam at high capacities, with effective use ofminimum space requirements for the furnace and the convection componentsof the installation, these characteristics making the steam generatoradvantageous for use in a locomotive.

The steam generator of the installation involves a water cooled furnaceused in conjunction with steam generating water tubes, some of whichform the boundary walls of the furnace which is particularly adapted forthe burning of pulverized coal as fuel.

' In the interest of high ignition temperatures, and of completecombustion of fuel, high furnace temperatures are maintained in theprimary .or high temperature zone of the furnace. The combustion of thecoal in this zone results in the liberation of ash which is raised to atemperature above its fusion point or the fusion point of any of itsseveral constituent chemicals. Consequently, the individual particles ofmolten ash or slag, and larger particles resulting from the coalescingof several individual particles exist in suspension in the gases in thehigh temperature zone of the furnace and, somewhat beyond that zone.Some of these particles contact the furnace boundary surfaces and adherethereto. They are at first chilled and solidified by the proximity ofthe cooler surfaces of the water tubes of the furnace, the lowertemperatures of these tubes being maintained by fluid circulated throughthem. As a stratum of this chilled slag is built up from the wallsurface, a condition is ultimately reached which, due to the thermalresistance of the layer so formed, and due to the high temperatureexisting in the furnace, results in the surface stratum which normallyremains at the fusion temperature of the slag. Additional particles aredeposited thereon in molten condition, flow down the surfaces of thestratum on the furnace walls and, at high capacities, result in aconsiderable flow of moltenash to the furnace floor. This flow of excessmolten ash is, in the illustrative installation continuously dis posedof so as to prevent such an accumulation the'efiicient operation of thefurnace.

15 Claims. (Cl. 122--328) Other particles of molten slag remain insuspension in the gases as they flow from the furnace and throughsucceeding gas passages. Some of these remaining particles contact thewalls of these passages which, in the illustrativ installation, areformed by heat absorbing fluid conducting tubes. Under these conditionsheat is radiated from the suspended particles as well as from the gasesin which the particles are suspended. This heat is radiated to the wallsand is absorbed and the degree of radiation and absorption varies withthe temperature differential between the particles and the heatreceiving wall surfaces. Also, this differential is, in turn, dependentupon the cleanliness of the wall surfaces, or the freedom of thosesurfaces from slag accumulation and the attendant thermal resistance andhigher surface temperatures caused thereby.

Some of these conditions are beneficial to one stage of the combustionand heat absorption process, but, are detrimenta1 to other stages. Inthe stage or zone where combustion is taking place there are importantadvantages resulting from the high temperature of the furnace boundarysurfaces. Examples of such advantages are the expedition and thecompletion of combustion. In stages or zones beyond the primarycombustion zone, and after substantially complete combustion iseffected, the major consideration is a high rate of heat absorption.This necessitates boundary walls at relatively low temperatures in orderto effect high temperature differentials between the water or otherfluid cooling the walls, and th combustion components transmitting heatthereto.

The present invention contemplates a steam generator which utilizes aconvection section and a furnace gas tempering section in combinationwith a furnace, all operating in such a manner as to effectively meetthe above indicated conditions and operating with a high availabilityfactor under different conditions such as those involved by the use ofcoals from different sources. Goals from different seams or differentsources used in pulverized form in furnaces all contain ash in greateror lesser amounts and the 'ashes from the different coals not onlydiffer in chemical constituency but also differ in fusion temperatures.

One object of the invention is to provide a steam generatinginstallation in which combustion gases and their suspended solids areeffectively cooled after. they leave the high temperaturezone of thefurnace and before then-reach the heat absorption zone formed by thespaced tubes of the convection section. Such tempering action isassociated with means providing for the elimination of the cooled ashsolids separated in the tempering zone, both of these actions preventingthe tubes of the convection section from receiving suchv accumulationsof. ash thatthey would soon become covered thereby to such an extentthat the installation would lose its optimum steam generating capacityas a result of the closing of the gas passages between adjacent tubes.

The invention will be described with reference to an illustrativeembodiment shown in the accompanying drawings, and further objects ofthe invention will appear as the description proceeds.

In the drawings:

Fig. 1 is a longitudinal vertical section through the illustrativeinstallation;

Fig. 2 is a partial sectional plan, or horizontal section, on the line2-2' of Fig. 1. This view shows only part of the installation involvingthe high temperature zone of the furnace and the gas tempering sectionof the installation immedi ately adjacent the furnace andreceivingfurnace gases directly therefrom;

Fig. 3 is a partial sectional plan complementar-y to Fig. 2, taken onthe same plane as Fig. 2 and showing the arrangement of the elements ofthe convection section, rearwardly of the gas tempering section shownin. Fig. 2;

Fig. 4 is a vertical section on the line 5-4 of 1 and looking in thedirection of the arrows. This figure shows the arrangement of the steamgenerating tubes. delineating. the walls, roof, and

floor of the high temperature section. of the furnace;-

Fig". 5 is; a vertical section on. the; multiple plane line 55 of Fig.1, looking in the direction of. the associated arrows and with: parts ofsome of. the tubes lid-bl: being: omitted for the sake of clarity;

Fig. 6 is a vertical section. through the installation on. the line E-5.of Fig; 1,. indicating the construction. of the, superheater;

Fig.7 is a transverse vertical section; on. the line t-'l of Fig- 3.,showing the construction; and arrangement of the tubes for the main.bank. M of steam. generating tubes;

8 is a transverse vertical section on the line: 8-tt of Fig. 1. showingthe. arrangement of the more. closely spaced tubes of the screensection', immediately rearwardly of. the: screen: sec.- tion.illustrated in Fig. 9:;

Fig. 9 is a transverse vertical section on the line 9-9 of Fig. 1.showing the arrangement of the more widely spaced. screen tubes disposedlust forwardly of. the screen tubes shown: in Fig. 8:;

Fig.. 10= is a multiple plane transverse, vertical section on the: lineill-4:0 of Fig. 1 showing the floor continuations oi the, wall tubesjust. for.- wardly of. the lower: ends of the tempering fluid ducts; and

Fig; 1-1 is a: transversevertical section on; the line ll-H of Fig. 1showing: the wall cooling tubes of the front transverse wall of thefurnace and also showing the arrangement of the burner tubes relative tothe: steam and: water drum and relative to the roof of the furnace.

The steam generator shown particularly in Figs. 1-, 2 and. 3 involves a.furnace Ill. the walls of which are defined. by steam generating tubesconnected at their upper ends to the steam and water d-rum 12. The steamand water drum ill.

(which may also be termed an upper fluid chamber) extends over thefurnace gas tempering section disposed immediately rearwardly of thefurnace Ill, and beyond the gas tempering section the drum extends overthe convection section which includes the main bank i l of steamgenerating tubes. and the superheater E6. The furnace is fired byburnerssuch as those indicated at 28-25. These are pulverized fuelburners supplied with a mixture of fuel and primary air through tubessuch as those indicated at and 2'5.

In the operation; of. the installation, the flames from the burners20-25 impinge against a stratum of molten slag upon the rearwardlyinclined furnace floor 30, the floor being formed by the floor tubesections such as those indicated at 32 and 3d of Fig. 4, and theirrefractory covering 35-. The combustion products then pass rearwardlyfrom the high temperature zone of the furnace and between. the uprightshadow tubes such as those indicated. at AilinFigs. l and 2. Each of.these shadow tubes has a refractory covering. such asthat indicated at462. The upper ends of these tubes are directly connected to the steam;and water drum #2 and their lower ends are connected to headers whichare in turn connected. to the drum i2 by appropriate downcomers' to belater referred to.

As the furnace gases contact the shadow tubes. some of the molten ash.particles suspended in the gases a h pon the refractory coverings ofthese tubes and. flow downwardly along these surfaces to the rearwardlyinclined. extension 41 of. the. furnace floor. this extension directinthe particles to aslag outlet opening. 48- above a. slag disposal zone.Accumulations of slag upon the surfaces of the tube refractory covering.forming the margins of this outlet are periodically removed by theoperation of the. swinging element 49 (Fig. ll pivoted at 59 andconnected to a fluid pressure cylinder '53 by a link. 56. This cylinderis pivoted; at its forward end to a fixed bracket 55.

After passing the shadow tubes 48-45 the gases are caused to flowthrough the tempering passages 68 and Bi (Figsean-d 1 01. Thesepassages, are formed between spaced groups of. inclined steam generatingtubes such as 65.-8J, the groups or these tubes forming downwardlyinclined ducts 9:2-94- (Fig. 2) for movement at a tempering. fluid such.as steam. or. air, transversely of. thepassages 6B and 61. $om-e of.these tubes form the central duct 93,, and the. remainder of the tubesform the remaining lateral: ducts 92 and. 9112 for the tempering nuid.This fluid passes to these ducts from appropriate tubular. connectionsor ducts. 'I-he fluid then passes. horizontally intoand across thetempering passages Git-81; through upright.- slots or openings such as98. 8d,. llllt and. illl Wig-.2) to lower the tempera.- ture of thefurnace: gases and their suspended solids and thereby cause the solidsto coalesce for downward separation from the gases in. the temperingzone. This zone may be considered as part. of. a slag separation zoneextending rearw-ardly from the. shadow tubes to a position rearwardl-yof the: tempering. ducts.

The: tempering fluid is distributed to the; ducts 92,. 93, and; 94. froma. transverse duct nee (Fig.1) which. is formed by the upper parts ofthe shadow tubes, the. tubes forming the walls of the ducts 912-94.. andthe roof of the installation. The upper ends of the shadow tubes are:bent so as to extend rearward-1y between the tubes forming. the ducts,as indicated in Fig. 1. 'Ihere is thus formed a transverse temperingfluid passage conmeeting the top ends of the three tempering fluidducts. The passage is in communication with an appropriate source oftempering fluid. It is also to be noted that the transverse temperingfluid passage 450 is formed in the space directly beneath theunprotected portion of the steam and water drum. This permits thetempering fluid, such as air, to pass between the roof tubes from theair duct 45I passing alongside the drum, see Figs. 4 and 5.

The tubes 65-81 forming the tempering fluid ducts are connected at theirlower ends to a transverse header I05 integrally joined at its ends tothe side headers I62 and I64 which are appropriately connected bydowncomers to the water space of the steam and. water drum I2. The upperends of the tubes 658I are connected directly to the steam and waterdrum I2 as indicated in Fig. 4. The middle duct 63 for tempering fluidhas its front wall formed by the steam generating tubes I60I, the spacesbetween these tubes being closed by a non-metallic refractory coveringsuch as that indicated at IIO. This refractory material is installed ina semi-plastic condition over theforward surfaces of the tubes andpreferably between radial metallic studs welded to the tubes. Thisconstruction is well known in the art as a stud tube wall. These tubesare also so arranged that the wall presents a concave face toward theoncoming gases. The tubes 'I0-'I5 delineating the rear wall of themiddle duct 93 are similarly arranged. This wall is also a stud tubewall including the refractory material H2. This wall is so spaced fromthe front wall of the duct that on one side the narrow upright slot I00is formed for the discharge of tempering fluid across the flow offurnace gases and other products of combustion through the passage 60.At the other side of the duct 94 is a similar slot 99 for the flow oftempering fluid to combustion products in the tempering passage 6|.

The tempering fluid duct 92 at the outer side of the passage 60 andopposite the slot or opening I00 is similarly formed by stud tubes 65-69and space closing refractory material as indicated at I I6 and H8 topresent an upwardly inclined slot or opening ml for tempering fluid flowinto the stream of combustion products flowing rearwardly through thepassage 60. In like manner, the duct 94, at the opposite furnace wall ofthe installation is formed by similarly arranged stud tubes 82-07, withthe spaces between these tubes closed by a refractory material indicatedat I20 and I22. The discharge slot 98 for tempering fluid flow acrossthe passage 6I is formed between the tubes 82 and 81.

The forward walls for the tempering fluid ducts 92 and 94 also presentconcave faces forwardly toward the oncoming combustion products, themarginal tubes 8! and 6! being disposed forwardly of the remainder ofthese walls to provide forwardlyfacing rims, or marginal surfaces,similar to those provided by the tubes I6 and 8| for the forward wall ofthe middle gas duct 93.

Directly rearwardly of the tempering passage 6I is a platten I26 formedby the forwardly inclined portions of the tubes I30I35. The upper endsof these tubes are directly connected to the steam and water drum I2 andtheir lower ends are appropriately connected into the fluid circulationof the installation. The platten terminates at the position indicated inFig. lat I39. jlo provide-this construction, the lower parts of tubesI35,. I33-and I3I are bent to extend outwardly to the wall tubes I35Aand I3IA (Fig. 2) to which they are joined by welding. The remainingplatten tubes are welded to these bent lower ends at I30A, I32A, and I34A.

A platten I40, similar to the platten I26, above described, is disposeddirectly rearwardly of the passage 60. It is formed by similarlyarranged tubes I4I-I46 and they are similarly connected into the fluidcirculation of the installation. The tubes of'the plattens I26 and I40are substantially contiguous and they form; radiant heat shields and gasflow deflectors between the furnace I0 and the tubes of the widelyspaced screen I (Figs. 3 and 9) and the more closely spaced tubes of thesecondary screen I52 (Fig. 8) disposed at the entrance of the convectionsection. The plattens divide the chamber between the screens I50I52 andthe tempering passages and BI into two zones, the rearward zone beingfree of the tubes, to promote the separation'of ash and the collectionof solidified ash in a subjacent ash disposal zone.

After passing the widely spaced tubes of the screen I50 and the tubes ofthe succeeding screen I62, the furnace gases pass through the flowequalizing space I54 just forward of the superheater I6.

The tubes of the screen I50 are connected at their lower ends to aheader I66 and their upper ends are in communication with the steam andwater drum I2 (Fig. 9). The header I00 preferably communicates directlyat its opposite ends with the lower side wall headers I62 and I64. Theseheaders are indicated in Fig. 3, as terminating just rearwardly of theheader I60 but they are connected to the rearward headers I66 and I68 bytubular connections I10 and I12.

The bank of tubes constituting the tubular screen I50 is three deep asindicated particularly in Fig. 3 of the drawings. There is a front rowof tubes such as I50A, an intermediate transverse row of tubes such asI503, and a rear row of tubes I50C. Each of these tubes is directlyconnected at its upper end to the steam and water drum (or upper fluidchamber) I2 and the vertical lower portions of the tubes I50B and I50Care weld connected to the rearwardly inclined lateral portion I50Dofeach of the front tubes 'I56A. Such connections are provided at thepositions indicated at I50F and I50H, in Fig. 1. Thus, the water supplyfor the tubes I 503 and I560 is afforded by their connections to theinclined lateral I50D which, in turn, is directly connected to the lowertransverse header, or

lower fluid chamber, I60, in the arrangement particularly indicated inFig. 1. The inclined laterals I561) are shown as connected to the sideof the header I60, while the upper part of this header is directlyconnected to the upright tubes of the screen I52.

The side headers I62 and I64 are also integral with a furnace front walltransverse header I6I (Figs. 1 and 11) from which the front wall coolingtubes such as I63 and I65 extend upwardly to the drum l2, in thearrangement specifically shown in Fig. 11.

The more closely spaced tubes of the screen section I52 are verticallydisposed directly above the header I60, as indicated in Figs. 3 and 8.

.Some of these tubes such as II82, are united by welding with othertubes of this screen section, such as I8 4-I86, in quasi-bifurcated tubeconstructions to provide an adequate number of .Wb si the s ree I w o nee s tat n an the chambers for periodic removal of ash therefrom: i

The particular arrangement of the vertical junction headers such as 202and 2| 2 (Fig. 6) and the construction and arrangement of the tubes andlower headers l 66 and I68 of the steam generating bank of tubes !4(Fig. 7) are such as to promote the deposition of combustion solids inthe ash receiving chambers 362--364 by avoiding obstructions to thefalling of solids into the chambers.

While in accordance with the provisions of the statutes we haveillustrated and described herein the best form of our invention nowknown to us,

those skilled in the art will understand that changes may be made in theform of the invention covered by our claims, and that certain featuresof our invention may sometimes be used to advantage without acorresponding use of other features. Y

What is claimed is:

1. 'In a fluid heat exchange installation, a furnace having its boundarysurfaces defined by fluid conducting tubes, burners, means supplyingpulverized fuel and air to the burners which fire the furnace attemperatures above the fusion temperature of the non-combustible residueof the fuel, said boundary surfaces including a floor receiving saidresidues to form a molten slag layer, the furnace floor being providedwith a slag discharge opening, and a slag clearer including a membernormally disposed out of the path of falling slag but periodicallymovable into and upwardly through said slag discharge opening to clearaway solidified slag which tends to -tubes are exposed, and convectionsteam generating and superheating surfaces arranged beyond the slagseparation zone in the direction of gas flow, the steam generatingsurfaces being presented by upright tubular elements connectedinto fluidcirculation of the generator and the shadow tubes having their upperends bent so as to cooperate with the steam generating tubes in forminga transverse tempering fluid passage from which fluid passes to thetempering fluid duct.

3. In a steam generator, a horizontally elongated and verticallyrestricted primary furnace, a fuel burning system including a set offuel burners downwardly firing the furnace at high combustion rates withan ash forming solid fuel, fluid cooled tubes defining the floor andother boundaries of the furnace, the furnace floor having a slagdischarge opening to which molten slag may flow from a position beyondthe burners, the fuel system with its burners being so co-ordinated withthe furnace floor that flames from the burners impinge upon a molten ashor slag stratum on the floor, a convection section heated by the furnacegases, means providing for the solidifying of slag particles in gassuspension before the gases pass to the convection section, said lastnamed means including vertically inclined steam generating tubesconstructed and-arranged to form furnace gas passages with ducts atopposite sides thereof, vertically inclined shadow tubes disposedforwardly of said gas passages, and means supplying said duets with atempering fluid which is injected into and mixed with the furnace gases.

4. In a steam generator, a horizontally elongated and verticallyrestricted primary furnace, steam generating tubes delineating the floorand other boundary surfaces of the furnace, a fuel burning systemincluding a set of pulverized fuel burners downwardly firing the furnaceat high combustion rates with an ash forming solid fuel, the furnacefloor being inclined downwardly away from a position opposite theburners for the flow of molten slag away from that position, forwardlyinclined and refractory covered steam generating shadow tubes extendingacross the gas outlet of the furnace, such shadow tubes beingindividually spaced transversely of gas flow, other upwardly andforwardly inclined steam generating tubes extending across the flow ofgases and connected into the fluid circulation system of theinstallation, said last mentioned tubes being constructed and arrangedto provide tempering fluid ducts through which a tempering fluid passesfor mixture with the furnace gases and consequent cooling of the ashparticles suspended in the furnace gases, means at the lower part of theinstallation for receiving solidified ash particles deposited from thefurnace gases,

chamber, means including tubes presenting water cooled slag collectingsurfaces defining a molten slag removal zone, means including steamgenerating water tubes arranged to form tempering fluid ducts for theintroduction of steam into mixing relationship with thestream of furnacegases leaving the slag removal zone, individually spaced shadow tubesdisposed across furnace gas flow forwardly of the point of introductionof the tempering fluid, and means presenting convection steam generatingand superheating surfaces arranged beyond the slag removal zone in thedirection of gas flow, the shadow tubes having their upper ends bent soas to cooperate with the steam generating tubes in forming a trans"-verse tempering fluid passage from which fluid passes to the temperingfluid duct.

6. A steam generator including apparatus for conditioning the productsof combustion of pulverized coal flowing rearwardly in a gas pass from ahigh temperature furnace to a convection section including spaced fluidheating tubes, said apparatus including a water cooled furnace having afloor normally covered with molten ash from the combustion of the coal,a tempering fluid system including fluid cooled ducts for introducingand mixing a tempering fluid with the stream of furnace gases, saidducts being inclined and extending upwardly and forwardly of said gaspass and through the furnace gases and having elongated longitudinallynarrow tempering fluid discharge ports opening toward the stream'offurnace gases, and individually spaced shadow tubes connected into afluid Oil! 11 solution system and disposed forwardly of fluid cooledducts, the shadow tubes having their upper ends bent so as to cooperatewith the steam generating tubes in forming a transverse tempering fluidpassage from which fluid passes to the tempering fluid duct.

7. Apparatus for conditioning products of combustion of pulverized coalflowing rearwardiy in a gas pass from a high temperature furnace "to aconvection section including spaced fluid heating tubes, said apparatusincluding a water cooled furnace (having a floor over which a slagstratum flows to a slag discharge opening, a tempering fluid systemincluding fluid cooled ducts for introducing and mixing a temperingfluid with the moving furnace gases, said ducts being inclined upwardlyand forwardly of said opening through the furnace gases and havingelongated longitudinally narrow tempering fiui-d discharge ports openingtoward the stream :of furnace gases, and spaced shadow tubes inclined ina manner similar to that or the .ducts and disposed in a transverse zonespaced forwardly of the ducts i 8. In a "water tube steam generator, aprimary furnace having means associated therewith for burning pulverizedfuel at fiurna'ce temperatures above the fusion temperatures of thenoncomrbustible in the fuel, the primary furnace having a horizontalextension formed by wall cooling steam generating tubes, groups offorwardly inclined steam generating tubes connected into the cirmutationof the generator and arranged to pre sent a furnace gas cooling barrieracross the furnace with an opening between the groups of tubes for theexit of furnace gases, groups of tubes being :also arranged relative toother similarly idlSDGSBd tubes to form tempering fluid ducts ofrelatively large free flow area exten ing into the furnace and havingtempering .iiuid noon-ts laterally of said passage, means "for supplyingsaid duets with tempering flu-id for flow of that fluid through saidports into mixing relationship with the furnace gases flowin throughsaid massage, a group of vertically inclined and individually spacedfluid cooled shadow tubes disposed transversely of the extension of the,primary furnace at a position forwardlt of said passage, an upright,platten consisting of a plurality cf upright steam generating tubes incontiguous relation and installed directly rearwardily of the gaspassage between the tempering fluid d'ucts, said platten acting as atarget wall to catch sprays of slag shot and acting to shield subsequentheat absorbing surfaces from the primary furnace, and a convectionsection including bank of steam generating tubes and a convectionsuperheater disposed rearwardly of said platten.

:9. a fluid heat exchange installation, a furnace having its boundarysurfaces defined by :tluid conducting tubes, burners, means supplyingpulverized fuel and air to the burners tor firing the -furnace attemperatures above the fusion temperature of the non-combustible residueof the fuel, said boundary sort-aces including a floor receiving saidresidues to dorm a molten "slag layer, the furnace floor being providedwith a slag discharge opening, a slag receiver beneath said opening, aslag clearer normally disposed out of the path of slag moving downwardlythrough said opening, and means for periodically moving the clearerupwardly through said slag discharge opening to clearaway solidifiedslag which tends .to close said opening. 7

1-0. Ina steam generator, :a longitudinally extended elevated steam andwater drum, a fur"- nace beneath the drum, "wall "means "providing a gaspass leading from the furnace and dis.- posed beneath the drum, :a bankof upright steam generating tubes exposed to the furnace gases in saidgas pass, superheater tubes of inverted U-s'hape disposed within the gaspass and nested to form a bank of spaced tubes, inlet header meansdisposed at one side of the gas pass out of the path of the furnacegases and connected with the corresponding ends of a plurality of thesuperheater tubes, and outlet header means "disposed at the other sideof the gas pass out of the path "of the furnace gases and connected tothe corresponding outlet ends of the plurality of superheater tubes.

'11. In combustion and fluid heat exchange apparatus, means providing aflow of furnace gases with solids in suspension therein, -uprighttempering fluid ducts extending across said how in a direction obliqueto the direction of the now, means for supplying said duct with atempering fluid at a temperature lower than that of said now or thesolids in suspension therein, and individually spaced fluid cooledshadow tubes disposed transver ely of said flow and forwardly saidducts, said ducts having side outlets for the discharge of the temperingfluid into :said the upper ends 'of'the shadow tubes being so cent as tooo-act with other elements including the walls of said ducts to form atransverse inlet passage or chamber from which the tempering fluid flows:to said ducts.

. apparatus vfor conditioning products of combustion of pulverized coalflowing horizontally in-a :gas pass from a high temperature furnace :toa convection section including spaced fluid heating tubes, saidapparatus including a water cooled furnace having a floor over which aslag stream flows to :a slag discharge opening, :a tempering fluidsystem including fluid cooled ducts .i-or introducing and mixing atempering ,rl'uid with the horizontally flowing stream of furmace gases,said ducts :beiug inclined and extending upwardlyand forwardly from saidopening through the furnace gases and having elongated longitudinallynarrow tempering fluid discharge ,ports opening toward the stream ofJim- .naoe gases, and rearwardly and downwardly Lin- :clined fluidcooled shadow tubes disposed transversely or said flow of combustionproducts an at a position forwardly of said ducts.

lnra water tube steam generator, a primary furnace having meansassociated .therew ithlfor burning pulverized fuel at furnacetemperatures above the fusion temperatures of the non-com.- bustib'le inthe fuel, the primary furnace having ahorizontal extension formed byWall cooling steam generating tubes, groups of forwardly inciined steamgenerating tubes connected into the circulation of the generatorandarranged to present a furnace cooling barrier across the verticalextent .of the furnace with. an opening 'between the groups of tubes forthe exit of furnace gases ,from the furnace, said groups of tubes beingalso arranged to forrultempering fluid ducts of relatively large freeflow area extending into the furnace and having tempering fluid ports atthe sides of said passage, means for supplying said duets with temperingfluid for how or" that fluid through said ports into mixing relationshipwith the furnace gases (flowing through said passage, a group ofverticaily inclined and individually spaced .fluid cooled shadow tubesacross the extension of the primary furnace at a position forwardly ofsaid passage, an upright platten consisting of a plurality of uprightsteam generating tubes in contiguous relation and installed as a canopydirectly rearwardly of the gas passage between the tempering fluidducts, said platten acting as a target wall to catch sprays of slag shotand acting to shield subsequent heat absorbing surfaces from the primaryfurnaces, a convection section including a bank of upright steamgenerating tubes and a bank of upright superheater tubes disposedrearwardly of said platten, and lower headers disposed along the sidesof the installation in the zone of the convection section, the tubes ofsaid convection section having their lower parts bent outwardly fordirect connection with said last mentioned headers.

14. In a fluid heat exchange installation, a furnace having its boundarysurfaces defined by fluid conducting tubes, burners, means supplyingpulverized fuel and air to the burners for firing the furnace attemperatures above the fusion temperature of the non-combustible residueof the fuel, said boundary surfaces including a floor receiving saidresidues to form a molten slag layer, the furnace floor being providedwith a slag discharge opening, a slag clearer including a membernormally movable into said slag discharge opening to clear awaysolidified slag which tends to close said opening, a convection sectionheated by the furnace gases, and a bypass construction including conduitmeans causing some of the furnace gases to pass through said opening andjoin the remainder of the gases at a position rearwardly of theconvection section.

15. In a furnace having an opening at its lower part for the dischargetherethrough of molten slag, means firing the furnace with a slagforming fuel at temperatures above the fusion temperature of the slag, aslag clearer having a part constructed and arranged to impact and removeslag bodies accumulated at said opening, means for movably mounting saidpart externally of and beneath the furnace, and means for moving saidpart upwardly toward said opening and across the path of slag flowdownwardly from said opening.

ERVIN G. BAILEY.

RALPH M. HARDGRO-VE.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 707,021 Schulz Aug. 12, 1902 863,597 Freeman Aug. 20, 19071,298,530 Mann Mar. 25, 1919 1,548,834 Foresman Aug. 11, 1925 1,729,217Hufschmidt Sept. 24, 1929 1,826,029 Smith Oct. 6, 1931 1,858,451 CoutantMay 17, 1932 1,874,487 Franklin Aug. 30, 1932 1,887,891 Roosen Nov. 15,1932 1,925,026 Austin Aug. 29, 1933 1,947,225 Pflager et al Feb. 13,1934 2,231,970 Toomey et a1 Feb. 18, 1941 2,242,762 Shellenberger May20, 1941 2,346,715 Woodard et a1. Apr. 18, 1944 2,393,205 Tiemeier Jan.15, 1946 2,399,884 Noack May 7, 1946 2,551,945 Harvey May 8, 1951FOREIGN PATENTS Number Country Date 13,960 Great Britain July 6, 1905

